Alcohol fuel operation conversion means for internal combustion engines

ABSTRACT

A modified carburetion and manifold arrangement to enable internal combustion engines to efficiently use fuels such as alcohols having high latent heat of vaporization. A variable venturi carburetion means (30) is combined with two manifolds-one (20) being larger for use during medium to high power operation and a second smaller manifold (24) for starting and low power operation.

The invention concerns means by which automotive piston internalcombustion engines may be converted to operate on ethanol and methanolfuel.

Following the Oil Shock of 1973, considerable experimentation wasundertaken into the use of alcohol fuels as fuel extenders or as fuelsin their ownright. In countries where organic feedstocks can besuccessfully grown in large quantities for the production of ethanol, orwhere natural gas is readily available for conversion into methanol, theuse of alcohol fuels is well established.

In most cases, engines converted to alcohol fuel operation wereoriginally manufactured to operate on gasoline. As a result ofdeficiencies in the conversion method, the operation of convertedvehicles is often less than satisfactory. Disabilities experienced inalcohol-fuelled engines are: difficulty in starting, stumbling and roughrunning when cold, stalling due to carburettor icing after operating atlow power, excessive emissions and generally poor fuel economy. Attemptshave been made to rectify the starting and cold running problems bychanging to an alternative supply of gasoline before stopping theengine, the starting and running the engine on the reserve supply ofgasoline until it reaches operating temperature.

The present invention aims generally to provide a means of converting agasoline powered automotive engine to alcohol fuel operation in such away as to eliminate or minimise the abovementioned operating problems.More particularly the present invention aims at providing improvementsin various aspects of engine design which are intended to achieveimproved engine performance when using alcohol or alcohol based fuelsand which can be used independently or in combination.

In accordance with a first aspect of the present invention there isprovided a caburetion and manifolding means to allow the efficientoperation of piston internal combustion engines on fuels having a highlatent heat of vaporisation such as ethanol and methanol, comprising avariable venturi type carburetion means, a first and larger manifoldingmeans to be used during medium to high power operation, and a second andsmaller manifolding means to be used during starting, idling and lowpower operation. Conveniently said improvement comprises providingpassage means discharging said filtered heated air immediately upstreamof the fuel discharge orifice. Preferably, the filtered heated air isheated by exhaust gases from said engine.

According to a preferred aspect of the present invention a butterflyvalve is provided to regulate the flow of fuel-air mixture through thesaid first and larger inlet manifolding means, the flow of fuel-airmixture through the said second and smaller inlet manifolding meansbeing taken off from a point upstream of the said butterfly valve andthence regulated by a barrel type valve, the operating means of whichare sequentially linked to the operating means of the said butterflyvalve. In accordance with a preferred embodiment, the auxiliary manifolddistribution arrangement includes means for heating the fuel/air chargepassing there through. To achieve this heating, a transversely extendingsection of the auxiliary manifold distribution arrangement is providedwith passage means in heat exchange relationship therewith adapted topass fluid from the engine cooling system, conveniently the thermostatbypass circuit.

Preferably an electrically operating auxiliary heating means may beprovided upstream of the secondary throttle means adapted to heat andassist in vapouring fuel only during engine start up.

According to a further aspect of the present invention there is provideda manifold arrangement for induction of a fuel/air charge into a sixcylinder engine, wherein the said first and larger inlet manifoldingmeans is made with a circular entry opening in area one unit, leading torunners of an internal rectangular shape, a smooth transition fromcircular to rectangular shape occurring between the said inlet openingand the branching of the separate runners for cylinders 3 and 4, heightof the said runners being constant throughout the said manifolding meansat 65% of the diameter of the said inlet opening and width of the saidrunners decreasing smoothly such that the cross-section area of the saidrunners is 57% of the area of the said inlet opening at the point ofbranching of the separate runners to cylinders 3 and 4, 51% of the areaof the said inlet opening at a point mid-way between the point of thepreceding dimension and the point of branching of the separate runnersto cylinders 1 and 2 and 5 and 6, 46% of the area of the said inletopening at the said point of branching of the said separate runners tocylinders 1 and 2 and 5 and 6, 41% of the area of the said inlet openingat the point where the separate runners to all cylinders debouch intotheir respective cylinder head inlet ports.

Conveniently, wherein the said round inlet opening leads to two firstshort runners in which the said smooth transition to a rectangularinternal cross-sectional shape occurs, the general axis of the saidfirst runners making an angle of 60 degrees with a reference planenormal to the longitudinal axis of the engine on which the saidmanifolding means is mounted, and the axes of the said separate runnersto cylinders 3 and 4 being more or less normal to the axes of the twosaid first short runners and converging to make an angle of 30 degreeswith the said reference plane before turning finally to parallel thesaid reference plane at the point of entry to their said respectivecylinder head inlet ports; and at a point immediately downstream of thepoints of branching of the said separate runners to cylinders 3 and 4,the said manifolding means recurves through 45 degrees to provide twomore or less straight long second runners which, at a point approachinga point adjacent the cylinder head inlet ports for cylinders 2 and 5,join two shorter curving third runners which turn towards the enginethrough 105 degrees and bifurcate into the separate runners respectivelyfor cylinders 1 and 2 and 5 and 6, the said separate runners tocylinders 1 and 6 diverging outwards from the said reference plane at 15degrees before turning finally to parallel the said reference plane atthe point of entry to their said respective cylinder head inlet portsand the said separate runners to cylinders 2 and 5 diverging inward atan angle of 30 degrees to the said reference plane before turningfinally to parallel the said reference plane at the point of entry totheir said respective cylinder head inlet ports.

The present invention will be more readily understood by reference tothe following description of preferred embodiments given in relation tothe accompanying drawings, in which:

FIG. 1 combines a side view of a carburettor and throttle block uponwhich it is mounted, showing the throttle actuating mechanism, and alongitudinal sectional viewof an air horn connected to the carburettor;

FIG. 2 is a transverse sectional view along line A--A of FIG. 4, of thethrottle block upon which the carburettor is mounted, the main inletmanifold and the auxiliary inlet manifold;

FIG. 3 is a side view of the arrangement of a means of providing asupply of heated air to the air horn fixed to the carburettor; and

FIG. 4 is a plane view of a main inlet manifold and throttle block inwhich the internal shaping of the left hand half of the main inletmanifold is shown in broken line, and in which the right hand half hasbeen removed, its outline being shown in broken line, revealing thearrangement of the auxiliary inlet manifold beneath it.

With reference to FIG. 1, variable venturi carburettor 51 is preferablyof the SU type, the operating principle of which is well-known in theart. Air horn 52 is fixed to the intake opening of the said carburettor,said air horn being made with an extension part 54 which projects intothe said carburettor opening and abuts the raised bridge in which issituated the fuel discharge orifice. Said extension part is providedwith a duct 55 which discharges a flow of filtered air heated by theexhaust gas stream of the engine immediately upstream of the carburettordischarge orifice.

With reference to FIG. 3, air from the engine air cleaner enters an airheater loop 29 through pipe 27, passing to duct 55 in air horn 52 viapipe 53. Said air heater loop projects into the engine exhaust stream ata suitable location in the exhaust manifold or exhaust pipe and mayembody one or more coils if additional surface is required. Pipe 53 islagged with an insulating covering if it is if any length.

With refernece to FIG. 2, said carburettor, from which the throttlebutterfly valve has been removed, is mounted upon throttle block 30which is provided with throttle butterfly valve 18 carried upon spindle7. Said throttle block is fixed to the carburettor mounting flange 31 ofa replacement main inlet manifold 20. Immediately upstream of the saidthrottle butterfly valve, in the floor of duct 42 in the said throttleblock in which the said throttle butterfly valve is accommodated, islocated diversion port 33. Said diversion port passes downward to barrelvalve 19 carried upon spindle 16 and accommodated in bore 43 in thelower part of the said throttle block. With throttle butterfly valve 18closed, atmospheric pressure causes a flow of fuel-air mixture downdiversion port 33, through the said barrel valve, through duct 44,through the opening in flange 32, through short duct 21 to shortlongitudinal runner 22. The ends of the said short longitudinal runnerare joined to auxiliary inlet manifold runner 24 at the mid points ofeach of its half lengths by means of short ducts 23. Said auxiliaryinlet manifold runner is made with heating duct 25 inside it passingalong its length, said heating duct being incorporated into the enginecooling system thermostat bypass circuit. Connecting the said auxiliaryinlet manifold runner to the base of each of the openings of the inletports in the engine cylinder head on ducts 26. Main throttle operatingspindle 10 is accommodated in a bore in an extension 17 of the saidthrottle block.

With reference to FIG. 4, throttle block 30 is fixed to carburettormounting flange 31 of main inlet manifold 20 and flange 32 of the saidauxiliary inlet manifold. Duct 21 joins the said auxiliary inletmanifold flange to short longitudinal runner 22, the ends of which arejoined by short ducts 23 to the mid points of each half length of thesaid auxiliary inlet manifold runner. Heating duct 25 enters at one endof the said auxiliary inlet manifold runner, passing along its length toemerge at the other end. The said auxiliary inlet manifold runner isjoined to the lower opening of each inle port in the engine cylinderhead by ducts 26. In the main inlet manifold, that depicted being for asix cylinder engine, entry opening 34 is made 43 mm in diameter, theinternal cross-sectional shape of the said manifold transitioningsmoothly from the said circular entry to a rectangular shape by thecommencement of the first runner junction. The internal cross-sectionalshape of the remainder of the said main inlet manifold runners isrectangular with a vertical dimension of 29 mm and with the cornersfilled with a fillet of 4.5 mm radius. The width of the said inletmanifold runners is: at point 35, 32 mm; points 36, 28 mm; points 37, 26mm; points 38, 23 mm. In an alternative embodiment of the main inletmanifold made for greater power output, entry opening 34 is made 51 mmin diameter and the vertical internal dimension of the runners is made36 mm. Carburettor mounting flanges 55 are provided for twincarburettors, their entry openings in the preferred embodiment being 38mm in diameter. The volume of fuel-air mixture distributed to eachcylinder in a particular engine type is tuned by slightly modifyingshapes 39, 40 and 41. With reference to a plane normal to thelongitudinal axis of the said inlet manifold, the main inlet manifoldrunners to cylinders two and five are curved inward by approximatelythirty degrees, the runners to cylinders one and six diverging from themby approximately fortyfive degrees. The runners to cylinders three andfour diverge from the entry runner by approximately ninety degrees. Thesaid main inlet manifold is fixed to the said cylinder head inn a metalto metal contact to promote its heating.

With reference to FIGS. 1 and 4, throttle butterfly valve spindle 7 isoperated by lever arm 8 which is pivotally attached to link 9, the otherend of which carries pin 13 engaged in curved slot 12 on cam plate 11.Cam plate 11 is carried on spindle 10, the other end of which carriesthe main throttle operating lever arm (not shown). Barrel valveoperating spindle 16 is operated by lever arm 15, on the outer end ofwhich is carried roller 14, said roller being held in contact with theedge of camplate 11 by a suitable spring (not shown). In operation,initial movement of the said main throttle operating lever arm causescam plate 11 to rotate, roller 14 coacting with its edge displacinglever arm 15 and rotating spindle 16 to progressively open the saidbarrel valve and admit an increased flow of fuel-air mixture to the saidauxiliary inlet manifold. Pin 13 rides in slot 12, having no effect uponthe position of throttle butterfly valve spindle 7 until rotation ofcomplete 11 causes pin 13 to contact the end of slot 12. Furtherrotation of spindle 10 then causes the said throttle butterfly valve tobe progressively opened.

Where starting proves to be a problem, provision is made for a smallelectric heating coil to be exposed to the flow of fuel-air mixtureimmediately upstream of the diversion port depicted as 33 in FIG. 2.Said heating coil is provided with electrical current through the engineignition switch, said current being interrupted by a thermostatic switchreferencing the temperature of pipe 53 depicted in FIGS. 1 and 3.

The claims defining the invention are as follows:
 1. A carburetion andmanifolding arrangement to allow the efficient operation of asix-cylinder internal combustion engine on fuels having a high latentheat of vaporisation such as ethanol and methanol comprising a variableventuri type carburetion means, a first and larger inlet manifoldingmeans to be used during medium to high power operation, and a second andsmaller inlet manifolding means to be used during starting, idling andlow power operation wherein the first and larger inlet manifolding meansleads to a respective cylinder-head inlet port for each cylinder and ismade with a circular central entry opening having a predetermined area,leading by branching to a separate runner of an internal rectangularcross-sectional shape for each cylinder, a smooth transition fromcircular to rectangular shape occurring between the entry opening and abranching point of the separate runners for cylinders 3 and 4, theheight of the runners being constant throughout the first and largermanifolding means at 65% of the diameter of the entry opening and thewidth of the runners decreasing smoothly such that the cross-sectionalarea of the runners is 57% of the area of the entry opening at thebranching point of the separate runners to cylinders 3 and 4, 51% of thearea of the entry opening at a point mid-way between the branching pointof the separate runners to cylinders 3 and 4 and a branching point ofthe separate runners to cylinders 1 and 2 and 5 and 6, 46% of the areaof the entry opening at the branching point of the separate runners tocylinders 1 and 2 and 5 and 6, and 41% of the area of the entry openingat each point where the separate runners to all cylinders debouch intotheir respective cylinder head inlet ports.
 2. A manifolding arrangementin accordance with claim 1 wherein the engine has a longitudinal axisand the circular entry opening leads to two first short runners in whichthe smooth transition to a rectangular internal cross-sectional shapeoccurs, the general axis of the first short runners making an angle of50 degrees with a reference plane normal to the longitudinal axis of theengine on which the first and larger manifolding means is mounted, andthe axes of the separate runners to cylinders 3 and 4 beingsubstantially normal to the axes of the two first short runners andconverging to make an angle of 30 degrees with the reference planebefore turning finally to parallel the reference plane at the point ofentry to their respective cylinder head inlet ports and at a pointimmediately downstream of the points of branching of the separaterunners to cylinders 3 and 4, the first and larger manifolding meansrecurves through 45 degrees to provide two substantially straight longsecond runners which, at a point approaching a point adjacent thecylinder head inlet ports for cylinders 2 and 5, join two shortercurving third runners which turn towards the engine through 105 degreesand bifurcate into the separate runners respectively for cylinders 1 and2 and 5 and 6, the separate runners to cylinders 1 and 6 divergingoutwards from the reference plane at 15 degrees before turning finallyto parallel the reference plane at the point of entry to theirrespective cylinder head inlet ports and the separate runners tocylinders 2 and 5 diverging inward at an angle of 30 degrees to thereference plane before turning finally to parallel the reference planeat the point of entry to their respective cylinder head inlet ports. 3.A manifolding arrangement in accordance with claim 2 wherein circularinlet openings are provided for the mounting of dual carburetion means,said dual carburetion inlet openings being situated at each point wherethe substantially straight long second runners join the shorter curvingthird runners, said dual carburetion means inlet openings being coveredby blanking plates when the central entry opening is in use and viceversa, the diameter of the dual carburetion means inlet openings beingmade approximately 84% of the diameter of the central entry opening. 4.A manifolding arrangement in accordance with claim 3 wherein prominencesare provided on internal walls of the first and larger inlet manifoldingmeans adjacent both sides of the point of branching of the separaterunners to cylinders 3 and 4 and on the outer side of the point ofbranching of the separate runners to cylinders 1 and 6, the height andshape of the prominences being modifiable to provide a fine adjustmentof the distribution of fuel-air mixture to individual cylinders.
 5. Areplacement carburetion and manifolding means adapted to replace anexisting carburetion and manifolding means to enable efficient operationof a reciprocating internal combustion engine on fuels having highlatent heat of vaporization such as ethanol and methanol, saidreplacement carburetion and manifolding means comprising:a variableventuri carburettor adapted to supply a fuel/air mixture to themanifolding means for said engine; an air intake means for saidcarburettor arranged to supply a main stream of air to said carburettor;secondary air supply means leading a secondary stream of heated filteredair to a position adjacent to a discharge orifice of said carburettorleading to said manifolding means, and said manifolding means comprisinga first larger inlet manifold to be used during medium to high poweroperation of the engine, and a second and smaller inlet manifold to beused during starting, idling and lower power operation.
 6. A replacementcarburetion and manifolding means according to claim 5, wherein saidsecondary air supply means leads said secondary air stream to a positionimmediately upstream of said discharge orifice of the carburettor.
 7. Areplacement carburetion and manifolding means according to claim 5,wherein said secondary air stream is heated by heat exchange withexhaust gases of said engine.
 8. A replacement carburetion andmanifolding means in accordance with claim 5, wherein a first valve isprovided to regulate flow of the fuel/air mixture from the carburettorto the first inlet manifold, a second valve is provided to regulate flowof the fuel/air mixture from the carburettor to the second inletmanifold, the flow of the fuel/air mixture to the second inlet manifoldbeing taken from the flow of fuel/air mixture of the first inletmanifold at a position upstream of the first valve, operating means forsaid first and second valves being operationally linked whereby duringstart up and the idle when said first valve is initially closed, saidsecond valve is progressively opened to supply fuel/air mixture via saidsecond inlet manifold prior to said first valve opening progressivelyfrom an off, idle condition of operation by which time said second valveis fully open.
 9. A replacement carburetion and manifolding meansaccording to claim 8, wherein said first valve is a butterfly valve andsaid valve is barrel type valve, rotation of said first and secondvalves to effect opening or closing thereof being effected byinterconnected link and/or cam means operable by a single throttlecontrol member.
 10. A replacement carburetion and manifolding meansaccording to claim 8, wherein the flow of fuel/air mixture to the secondinlet manifold is heated by auxiliary heating means located between thefirst valve and the carburettor upstream of the position where saidfuel/air mixture flowing to said second inlet manifold is taken from thefuel/air mixture flowing towards said first inlet manifold, saidauxiliary heating means being operable during start up of the engine andbeing inoperable once the secondary stream of heated filtered airreaches a predetermined temperature.
 11. A replacement carburetion andmanifolding means according to claim 8, wherein said first inletmanifold includes a first passage leading from said first valve into afirst longitudinal runner with a plurality of first branch passagesspaced along said longitudinal runner ending in first inlet manifoldports, said second inlet manifold comprising a second passage leadingfrom said second valve to a second longitudinal runner arrangement withsecond branch passages spaced along said second longitudinal runnerarrangement ending in second inlet manifold ports, each said secondinlet manifold port being located in a base region of a respective oneof said first inlet manifold ports whereby both said first and secondinlet manifold ports are arranged, when installed, to communicate withinlet ports of said engine.
 12. A replacement carburetion andmanifolding means according to claim 11, wherein the first passageenters said first longitudinal runner midway along its length.
 13. Areplacement carburetion and manifolding means according to claim 11 orclaim 12, wherein said second longitudinal runner arrangement comprisesa first runner duct and a second runner duct, said second passageentering said first runner duct midway along its length with said firstrunner duct communicating with said second runner duct at spacedlocations, said second runner duct including means for heating thefuel/air mixture flowing therethrough.
 14. A replacement carburetion andmanifolding means according to claim 13, wherein the means for heatingthe fuel/air mixture in said second runner duct comprises piping meansled through said second runner duct adapted to carry a heated fluid orgas.
 15. A replacement carburetion and manifolding means according toclaim 14, wherein the piping means forms part of the engine coolantcirculation system.